If the sorc has Noxious embers for free maximise, the LOTD for -50% sp, and the belt from amrath that gives 75% to cold spells, then ya, the sorc WILL have enough sp to last, and he will dish out some pretty good damage spamming CoC and Polar Ray. But the fact of the matter is most sorcs don't have that. They don't have potency on their polar ray, and it is only hitting for around 300 a hit. Many don't know how to nuke.
In my shrouds, i will let in 2 casters, maybe even 3.. but that's if i know them.